Question: In chamfer matching, at any step, a pixel can be updated if the distances from some or all of its neighbours to an edge are known; Borgefors counts the distance from a pixel to a vertical or horizontal neighbour as 3 and to a diagonal neighbour as 4 to ensure the pixel values are integers. Why does this mean √ 2 is approximated as 4/3? Would a better approximation be a good idea?